1. Field of the Invention
The present invention relates to an optical deflection device, which controls a deflection direction of a light beam using a movable mirror. The present invention also relates to an optical switch, which controls couplings among optical fibers using the optical deflection device.
2. Description of the Related Art
An optical switch comprising movable mirrors, collimator lenses, input/output optical fibers and the like is described in WO01/95013A2. In the optical switch, a control for optimizing attitudes of movable mirrors related to a selected input/output path is executed as follows. First, the movable mirrors are driven based on a predetermined driving pattern, optical power of light in each driving signal is sampled, and a relation between the driving signal and the optical power of light is approximately calculated so as to obtain a curve. Next, the driving signal at a time when the optical power of light is maximized is estimated from the obtained approximate curve, and the movable mirrors are driven by the driving signal.
The method of controlling the attitudes of the movable mirrors described in WO01/95013A2 requires an operation of obtaining the approximate curve indicating the relation between the attitudes of the movable mirrors and the optical power of light to estimate the attitudes of the movable mirrors by which the optical power of light is maximized from the obtained approximate curve. To obtain the approximate curve, it is necessary to drive the movable mirrors in a comparatively broad range including the attitudes for maximizing the optical power of light and to sample the optical power of light.
For example, in U.S. Pat. No. 6,335,811, a method is described in which the attitude of the movable mirror after micro movement is maintained with the increase of the optical power of light by the micro movement of the movable mirror, the attitude is returned to that before the micro movement with the decrease of the optical power of light by the micro movement of the movable mirror, and these operations are repeated about each driving axis of the movable mirror. In this method, the movable mirror is repeatedly micro-moved in a predetermined order with respect to several predetermined directions.